Use CKEDITOR.tools.addFunction and CKEDITOR.tools.callFunction to handle communication with iFrame.
Change element name from script to span.
Upcast and downcast.
Refactor code. Create private FramedMathJax class. Use src to generate iFrane content.
Fix with IE8.
Move iFrame logic from iFrame to FramedMathJax object.
Fixed dataflow after refactoring.